Surgical instrument with rotary cutting member and quick release coupling arrangement

ABSTRACT

A surgical instrument for the dissection of bone and other tissue includes a spindle, a dissection tool and an adaptor disposed between the spindle and the dissection tool. The spindle includes a cavity and a male member projecting into the cavity. The adaptor includes a drive shaft that extends along an axis and includes a first end having a generally cylindrical cross-section and a centrally located aperture partially extending along the axis. The male member is carried by the spindle and extends into the aperture of the dissection tool. The cavity may define a drive portion and a tool receiving aperture. One or more alignment projections may extend from the drive portion into the tool receiving aperture.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This invention claims priority to U.S. Utility application Ser.No. 10/164,867 filed Jun. 7, 2002 and U.S. Utility application Ser. No.10/102,762 filed Mar. 21, 2002 and Provisional Application 60/277,639,filed Mar. 21, 2001, each incorporated herein by reference.

FIELD OF THE INVENTION

[0002] The present invention generally relates to surgical instrumentsfor use in the dissection of bone and other tissue. More particularly,the present invention relates to a dissection tool and a quick releasecoupling arrangement for a surgical instrument.

BACKGROUND OF THE INVENTION

[0003] In various surgical procedures, it is necessary to dissect boneor other tissue. Many conventional surgical instruments used for thedissection of bone or other tissue employ pneumatic or electrical motorsto rotate a cutting element. In their most basic form, such surgicalinstruments comprise a motor portion having a rotary shaft, a dissectiontool having a cutting or abrading element that is rotated by therotating shaft of the motor, and a coupling arrangement for connectingthe dissection tool to a spindle or collet of the rotary shaft. Thespindle or collet of the rotary shaft is usually housed within a basethat is attached to the motor.

[0004] Because it is frequently necessary to replace the dissectiontool, it is also known in the art to use a quick release coupling tosecure the dissection tool to the surgical instrument. An example ofsuch a quick release coupling is shown and described in commonlyassigned U.S. Pat. No. 5,505,737 entitled “Quick Release Coupling For ADissecting Tool.” The coupling device shown in U.S. Pat. No. 5,505,737includes a spindle attachment which is secured to a spindle of asurgical instrument. The spindle attachment has a shaft engagementportion for engaging a shaft of the dissection tool. The shaftengagement portion of the spindle attachment is provided with aperturesthat terminate within a central bore of the engagement portion throughwhich the shaft of the dissection tool extends.

[0005] Surrounding the spindle attachment is a cylindrical sleeve havinga contact surface that engages several spherical locking members locatedwithin the apertures of the shaft engagement portion of the spindleattachment. A sleeve engagement member is coupled to the base of thesurgical instrument and is movable between retracted and extendedpositions.

[0006] As the sleeve engagement member is moved between the retractedand extended positions, it causes the sleeve of the surgical instrumentto be moved between an engaged and disengaged position with respect tothe dissection tool. When the sleeve is moved to the engaged position,the contact surface of the sleeve forces the spherical locking membersinward toward the central bore of the spindle attachment where thelocking members contact the shaft of the dissection tool, therebypreventing removal of the dissection tool from the surgical instrument.When the sleeve is moved to the disengaged position in which thespherical locking members are allowed to retract within the apertures,the dissection tool is able to be removed from the socket.

[0007] While known surgical tools including replaceable dissection toolshave proven to be acceptable for their intended applications, it remainsdesirable to further advance the pertinent art. For example, due to thehigh speed rotating action of the dissection tool, a need exists in theart for more precise alignment of the dissection tool within thesurgical instrument. Further, in past designs, the coupling mechanismhas not included means to limit the acceptance of non-approved toolshafts. Specifically, non-approved or qualified tool shafts may sufferfrom a number of problems. End users may improperly select a tool shaftof the incorrect strength for a given length, select the incorrectdiameter, or attempt to utilize the incorrect cutting head configurationbased on the motor design. Such variations in the tool shaft can resultin damage to the motor coupling assembly and supporting bearings in theattachment housing, result in extreme cutting tip flail at high speedpotentially causing injury to a patient and stressing the tool shaftwith the possibility for breakage. Additionally, a need exists in thepertinent art for an improved surgical tool which permits telescoping ofthe dissection tool relative to a fixed sleeve.

SUMMARY OF THE INVENTION

[0008] In one particular embodiment, the surgical instrument includes arotary spindle or shaft having a cavity, as well as a dissection toolreleasably received within the cavity. The dissection tool extends alonga longitudinal axis and includes a first end and a second end. The firstend of the dissection tool includes a cutting element, and the secondend a centrally located bore partially extending inwardly along thelongitudinal axis. A centrally located pin is carried by the spindle andextends into the bore of the dissection tool in a coupled engagement.

[0009] In another particular embodiment, the surgical instrumentincludes a fixed sleeve and a dissection tool rotatably disposed withinand partially extending from the sleeve. The surgical tool additionallyincludes a coupling arrangement for releasably engaging the dissectiontool. The dissection tool is translatable along its axis and relative tothe fixed sleeve between a retracted position and an extended position.

[0010] In yet another particular embodiment, the surgical instrument ofthe present invention includes a dissection tool, a housing, and acoupling arrangement carried by the housing releasably engaging thedissection tool. The dissection tool includes a reduced diameterportion. The coupling arrangement includes a plurality of lockingmembers engaging the reduced diameter portion. In a preferred aspect,the reduced diameter portion is defined by a plurality of planar sides.Still more preferably, the number of planar sides of the plurality ofplanar sides is equally divisible by the number of locking members ofthe plurality of locking members.

[0011] A potential advantage of the present invention is the provisionof a surgical instrument for the dissection of bone and other tissue inwhich the dissection tool is precisely centered within the surgicalinstrument.

[0012] Another potential advantage of the present invention is theprovision of a surgical instrument for the dissection of bone and othertissue which inhibits attachment of dissection tools that are notdesigned for operation in the surgical instrument. Still a furtheraspect of the present invention is the provision of a dissection toolhaving a coupling end with drive surfaces and at least one longitudinalalignment surface. In one preferred embodiment of the invention, thealignment surface extends internally to the drive surface. In anotherpreferred embodiment the alignment surface is disposed on the externalsurface of the dissection tool.

[0013] Another potential advantage of the present invention is theprovision of a surgical instrument for the dissection of bone and othertissue in which a dissection tool is more securely attached to thesurgical instrument to prevent unwanted movement of the distal end ofthe dissection tool.

[0014] Another potential advantage of the present invention is theprovision of a surgical instrument for the dissection of bone and othertissue in which a tactile feeling is generated upon insertion of thedissection tool into the surgical instrument so as to provide anindication to the user of proper engagement of the dissection tool.

[0015] Another potential advantage of the present invention is theprovision of a surgical instrument for the dissection of bone and othertissue which includes a rotationally fixed sleeve and a rotatabledissection tool disposed in the sleeve and translatable relative to thesleeve between a retracted position and an extended position.

[0016] Still a further object of the present invention is the provisionof a tool shaft and quick release coupler that may provide threedimensions of alignment during a coupling procedure. The assembly mayprovide transverse, longitudinal and rotational alignment in relation tothe longitudinal axis.

[0017] In yet a further aspect of the present invention, a tool memberis provided that includes an internal engagement portion and acooperating external engagement portion. In a preferred aspect, theinternal engagement portion permits axial alignment by receiving aprojection and the external engagement portion is adapted to receivetorque transmission from a surrounding coupler. Still more preferably,the internal engagement portion and the external engagement portion haveaxially overlapping sections over at least a portion of their length.

[0018] In yet an additional aspect of the present invention, theexternal surface of the attachment housing is configured with multipletapers to increase tool tip visibility.

[0019] Still further, another preferred aspect of the present inventionis the provision of tactile feedback upon the engagement of theattachment housing with the motor housing. In a preferred aspect, theattachment housing is joined to the motor housing with an interferencefit. In a further preferred aspect, the engagement between the motorhousing and attachment housing is confirmed by an audible sound.

[0020] In another aspect, the present invention provides quick releasecoupling members to engage a dissection tool.

[0021] In still a further aspect, the present invention providesdissection tools with nonperpendicular driving surfaces.

[0022] In yet a further aspect, the present invention provides acoupling assembly with an improved alignment mechanism.

[0023] In still a further aspect, the present invention provides anadaptor for coupling to the motor.

[0024] Additional advantages and features of the present invention willbecome apparent from the following description and appended claims,taken in conjunction with the accompanying drawings.

[0025] Further areas of applicability of the present invention willbecome apparent from the detailed description provided hereinafter. Itshould be understood that the detailed description and specificexamples, while indicating the preferred embodiment of the invention,are intended for purposes of illustration only and are not intended tolimit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

[0027]FIG. 1 is an illustration of a surgical dissection tool accordingto the present invention use in a human patient.

[0028]FIG. 2A is a partially exploded perspective view of a surgicaldissection tool according to the present invention.

[0029]FIG. 2B is a partially exploded perspective view of a surgicaldissection tool according to the present invention.

[0030]FIG. 2C is an assembled perspective view of the surgicaldissection tool of FIG. 2A.

[0031]FIG. 3 is a partial cross-sectional side view of the surgicaldissection tool of FIG. 2C.

[0032]FIG. 4 is an exploded perspective view of a portion of thesurgical dissection tool of FIG. 3.

[0033]FIG. 5A is a partial cross-sectional side view of a portion of thesurgical dissection tool of FIG. 3 rotated 90° illustrating the unlockedposition.

[0034]FIG. 5B is a partial cross-sectional side view of the surgicaldissection tool of FIG. 5A with a portion thereof rotated to illustratethe locked position.

[0035]FIG. 6A is a side view of a dissection tool according to anotheraspect of the present invention.

[0036]FIG. 6B is an end view of the dissection tool of FIG. 6A.

[0037]FIG. 6C is a cross-section taken along line 6C-6C in FIG. 6A.

[0038]FIG. 6D is the cross-sectional view of FIG. 6C illustrating thedriving socket.

[0039]FIG. 7A is a cross-section of an alternative drive area of adissection tool according to another aspect of the present invention.

[0040]FIG. 7B is a cross-section of an alternative drive area of adissection tool according to another aspect of the present invention.

[0041]FIG. 7C is a cross-section of an alternative drive area of adissection tool according to another aspect of the present invention.

[0042]FIG. 8A is an exploded perspective view of a portion of a surgicaldissection tool according to still another aspect of the presentinvention.

[0043]FIG. 8B is a partial cross-sectional perspective view of a portionof FIG. 8A.

[0044]FIG. 8C is a partial cross-sectional side view of the assembledapparatus of FIG. 8A in the unlocked position.

[0045]FIG. 8D is a partial cross-sectional side view of the assembledapparatus of FIG. 8A in the locked position.

[0046]FIG. 9A is a partial cross-sectional side view of a potion of asurgical dissection tool according to another aspect of the presentinvention.

[0047]FIG. 9B is a partial end view of FIG. 9A.

[0048]FIG. 10A is a side view of an alternative drive area of adissection tool according to another aspect of the present invention.

[0049]FIG. 10B is a side view of alternative drive area of a dissectiontool according to another aspect of the present invention.

[0050]FIG. 10C is a side view of alternative drive area of a dissectiontool according to another aspect of the present invention.

[0051]FIG. 11A is a side elevational view of a surgical instrument forthe dissection of bone and other tissue according to the teachings ofanother embodiment of the present invention.

[0052]FIG. 11B is a cross-sectional view of a portion of the surgicalinstrument for the dissection of bone and other tissue according to theteachings of FIG. 11A.

[0053]FIG. 11C is a perspective view of a proximal end of a dissectiontool used with the surgical instrument for the dissection of bone andother tissue according to the teachings of FIG. 11B.

[0054]FIG. 11D is a side view of the dissection tool used with thesurgical instrument for the dissection of bone and other tissueaccording to the teachings of FIG. 11B.

[0055]FIG. 12 is a partial cross-sectional view of a portion of thesurgical instrument for the dissection of bone and other tissueaccording to the teachings of another embodiment of the presentinvention.

[0056]FIG. 13A is a perspective view of a proximal end of a dissectiontool of a surgical instrument for the dissection of bone and othertissue according to the teachings of still a further embodiment of thepresent invention.

[0057]FIG. 13B is a cross-sectional of a portion of a surgicalinstrument for the dissection of bone and other tissue according to theteachings of FIG. 13A, the dissection tool shown in a fully retractedposition.

[0058]FIG. 13C is a cross-sectional view similar to FIG. 13Billustrating the dissection tool in a fully extended position.

[0059]FIG. 14 is a perspective view of a proximal end of a dissectiontool of a surgical instrument for the dissection of bone and othertissue according to the teachings of a further preferred embodiment ofthe present invention.

[0060]FIG. 15A is a perspective view of a proximal end of a dissectiontool of a surgical instrument for the dissection of bone and othertissue according to the teachings of still a further preferredembodiment of the present invention.

[0061]FIG. 15B is a side view of the dissection tool according to theteachings of another preferred embodiment of the present invention.

[0062]FIG. 15C is a cross-sectional view taken along the line 15C-15C ofFIG. 15B.

[0063]FIG. 15D is a cross-sectional view taken along the line 15D-15D ofFIG. 15B.

[0064]FIG. 16 is a cross-sectional view similar to FIG. 15D illustratinga dissection tool according to the teachings of another preferredembodiment of the present invention.

[0065]FIG. 17A is a partial cross-sectional view of a portion of asurgical instrument for the dissection of bone and other tissueaccording to the teachings of another preferred embodiment of thepresent invention.

[0066]FIG. 17B is an enlarged cross-sectional view of FIG. 17A,illustrating the closure member in a clamped position securing thedissection tool to the input shaft.

[0067]FIG. 17C is a perspective view of the proximal end of a dissectiontool of the surgical instrument for the dissection of bone and othertissue according to FIG. 17B.

[0068]FIG. 17D is an end view of the dissection tool of FIG. 17C.

[0069]FIG. 17E is a cross-sectional view taken along the line 17E-17E ofFIG. 17D.

[0070]FIG. 18A is a partial cross-sectional side view of still a furtherdissection tool coupling assembly according to another aspect of thepresent invention.

[0071]FIG. 18B is a perspective view of the dissection tool of FIG. 18A.

[0072]FIG. 19A is a partial cross-sectional side view of anotherdissection tool coupling assembly according to another aspect of thepresent invention.

[0073]FIG. 19B is a side elevational view of the dissection tool of FIG.19A.

[0074]FIG. 20A is a partial side elevational view of a dissection toolaccording to another aspect of the invention.

[0075]FIG. 20B is an end view of the dissection tool of FIG. 20A.

[0076]FIG. 21 A is a side elevational view of a coupling assemblyaccording to another aspect of the invention.

[0077]FIG. 21B is a perspective view of the coupling assembly of FIG.21A.

[0078]FIG. 22A is a partial cross-sectional view of the couplingassembly of FIG. 21A taken along line 22-22 illustrating the tool ofFIG. 20A prior to insertion.

[0079]FIG. 22B shows the coupling assembly of FIG. 22A illustrating thetool of FIG. 20A in the locked position.

[0080]FIG. 23 is a partial cross-sectional view of a rotor shaftassembly of the coupling assembly of FIG. 22A.

[0081]FIG. 24 is a partial cross-sectional view of the coupling assemblyof FIG. 22A with an attachment assembly in locking engagement.

[0082]FIG. 25A is a perspective view of a tool assembly according to thepresent invention prior to interconnection and FIG. 25B illustrates thetool assembly after interconnection.

[0083]FIG. 26 is a cross-sectional side view of the angled attachment ofFIG. 25A.

[0084]FIG. 27 is an enlarged partial cross-sectional side view of theinterconnection of the tool assembly of FIG. 25B.

[0085]FIG. 28 is a partial cross-sectional end view taken along line28-28 of FIG. 27.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0086] The following description of the preferred embodiments is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

[0087] Referring now to FIG. 1, there is shown a human patient Aundergoing a neurological operation. As is common practice, access tothe brain or other neurological structures often requires delicatedissection of bone and other tissues B to gain access. By way ofexample, dissection tool assembly 10 in accordance with one aspect ofthe present invention is shown being utilized to dissect a portion ofpatient A's bone and other tissue B adjacent to the surgical accesssite.

[0088] Referring now to FIGS. 2A-2C, a dissection tool assembly 10 forthe dissection of bone or other tissue is illustrated. Dissection toolassembly 10 includes a motor housing 12, coupled to air supply and hoseassembly 14 that supplies pressurized air to the motor and vents the lowpressure exhaust air away from the surgical site. Dissection toolassembly 10 further includes an attachment housing 16 and a dissectiontool 18. As shown in FIG. 2A, the distal portion 51 of motor housing 12includes a tapered leading portion 53 and a Double D connection region.The Double D region comprises a pair of opposed and substantiallyparallel planar portions interrupting the cylindrical body to define twoopposed substantially parallel cylindrical portions. These portions areseparated by junction 55 into a fixed segment having cylindrical portion54 and flat portion 52, and a movable segment having cylindrical portion58 and flat portion 56.

[0089] Referring now to FIGS. 2B and 3, attachment housing 16 includesan internal cavity 63 adapted and configured to engage distal portion 51of motor housing 12. In an initial position with first cylindricalportion 25 substantially abutting motor housing 12, attachment indicatormark 24 is in substantial alignment with unlocked indicator mark 22 onthe motor housing. In this position, dissection tool 18 may be insertedinto attachment housing 16 and be received in a coupling assembly(described later) within motor housing 12. Referring now to FIG. 2C,with dissection tool 18 inserted within attachment housing 16 andengaged in the coupling of the motor housing 12 (see FIGS. 3-5B),attachment housing 16 may be rotated in the direction of arrow 23 withrespect to motor housing 12. Movement in this direction moves attachmentindicator marking 24 into substantial alignment with the lockedindicator marking 15 on motor housing 12. As described further herein,such movement also operates the coupling assembly to lock dissectiontool 18 into driving engagement with the internal motor.

[0090] In a preferred aspect of the present invention, attachmenthousing 16 is adapted to engage the distal portion 51 of motor housing12 in an interference fit. Further, attachment housing 16 and distalportion 51 are configured to provide the user with tactical feedbackindicating positive engagement. More specifically, internal cavity 63includes an internal annular groove 46 carrying an O-ring 44. Distalportion 51 defines an external annular groove 48 adapted to receive aportion of O-ring 44. Thus, it will be understood that as attachmenthousing 16 is advanced over distal portion 51, O-ring 44 will beslightly compressed into grove 46 as it engages tapered front end 53 toan expanded inner diameter. When O-ring 44 is positioned over annulargroove 48, the compressed O-ring 44 will quickly relax into a smallerinner diameter shape engaging annular groove 48 providing the user witha tactile sensation. Preferably such tactile sensation will include botha vibration and auditory signal, indicating that the attachment is inthe proper position on motor housing 12. While the movement of O-ring 44into annular groove 48 provides tactile sensation of the properpositioning of attachment housing 16 with respect to motor housing 12,it will be appreciated that the attachment housing 16 is not positivelylocked to motor housing 12. Rather, the configuration of internal cavity63 closely matches the external configuration of distal portion 51 tocreate an interference fit sufficient to prevent accidental dislodgingof attachment housing 16 from motor housing 12. However, it will beunderstood that manual pulling along the longitudal axis of attachmenthousing 16 will easily dislodge the attachment housing from motorhousing 12. In this preferred aspect, it is contemplated that the userwill not have to operate any mechanical locking members to lock orunlock the attachment housing to the motor housing thereby easing theoperation for the end user.

[0091] In addition to the ease of coupling the attachment housing 16 tothe motor housing 12, it is preferred that the exterior contour of theattachment housing be contoured to provide optimum field of view of thedissection tool 18 dissection head 20 while at the same time providingsupport of tool shaft 19. More specifically, attachment housing 16includes a first cylindrical portion 25 having an external diameterslightly less than the external diameter of motor housing 12. Firstcylindrical portion 25 transitions through first taper 26 to a secondsmaller diameter cylindrical portion 28. The reduction in diametercontinues through tapered section 30 and into third cylindrical portion32 having still a smaller diameter than cylindrical portion 28. Finally,attachment housing 16 terminates in tapered portion 34.

[0092] It will be understood that there is a maximum line of sight 35through which an end user may still visualize dissection head 20. Thetransition points 27, 29 and 33 between the cylindrical portions and thesmall diameter tapering sections provide the first points of obstructionof line of sight 35. As best seen in FIG. 3, line of sight 35 intersectshigh point 27 and high point 33. In a preferred aspect of the presentinvention, it is contemplated that maximum line of sight 35 willsubstantially intersect at least two high points. Still further, it iscontemplated that second cylindrical portion have a diametersubstantially less than the line of sight to permit engagement with anoperator's fingers without undue interference with a maximum line ofsight. Still further, the transitions adjacent high points 27, 29 and 33are radiussed to remove an abrupt corner thereby lowering the height ofeach high point and increasing the maximum line of sight.

[0093] Referring to FIGS. 2B and 3, attachment housing 16 is providedwith an internal bore 17 adapted to receive a portion of dissection tool18. More specifically, internal bore 17 includes a plurality of bearingsadapted to rotationally support tool shaft 19. The tool shaft issupported by distal bearing 36 and intermediate bearing 38 and proximalbearing 40. In the preferred embodiment illustrated in FIG. 3, distanceD1 represents the distance between the distal bearing 36 and dissectionhead 20. It will be understood that this distance may vary depending onmany variables such as the length and diameter of the cutting tool head,diameter of the tool shaft, etc. Distal bearing 36 is located in thedistal most portion of cylindrical portion 32. It will be understoodthat the angle created by line of sight 35 and the longitudal axis ofdissection tool 18 is shown by angle A1. In the preferred embodimentillustrated in FIG. 3, this angle is approximately 10°. However, it iscontemplated that this angle A1 will vary from attachment to attachmentand is dependent on tube length and attachment diameter. Still anotherpreferred aspect of the present invention, tapered surface 34 on theleading tip of attachment housing 16 provides a smooth surface overwhich tissue and other obstructions may readily move. It will beunderstood that as the device is utilized for the dissection of bone andother tissue, thereto is a desire to minimize snagging on tissue orengaging other obstructions as the dissection tool assembly 10 isutilized in the patient. Furthermore, disposed internally of distaltaper 34, is an internal taper of internal bore 17 transitioning from alarge diameter at the distal-most end of internal bore to a smallerdiameter approaching the bearing assembly area. Internal taper 37 isprovided to permit some minimal flail of tool shaft 19 during operationwhile still rotationally supporting the shaft. It will be understoodthat spacing dissection head 20 from distal bearing 36 may induce someflail or angular deflection along the longitudal axis of tool shaft 19during operation.

[0094] Referring to FIG. 3, there is shown a pneumatically operatedmotor 80 associated with the dissection tool assembly 10 of the presentinvention. Motor 80 receives high pressure air from inlet hose 82. Highpressure air flows through outlets 84 and impacts vanes 86 to urgerotation towards air outlets 88. The air then exits through low pressureexhaust passage 90. It will be understood that the rotation of vanes 86drives rotor shaft 92. Although a pneumatic motor is shown for thepurpose of illustration, it will be understood that motors usingelectricity or other motive forces may be utilized with the presentinvention.

[0095] Referring now to FIGS. 3 through 5B, there is shown in detail acoupling assembly 102 in accordance with one aspect of the presentinvention. Referring more specifically to the exploded perspective viewof FIG. 4, coupling assembly 102 includes a collet housing 104 having ahelical slot 105 adapted to receive ball bearings 106, and a pair ofapertures 107 adapted to receive alignment balls 108. Coupling assembly102 further includes a housing spacer 110 and an O-ring 112 associatedwith posterior Double D-collet 114. Posterior Double D-collet 114 isspaced from anterior Double D-collet 118 by shim 116. The assemblyfurther includes O-rings 120 and 122 and tapered nose 124. A number ofthe remaining components are disposed within collet housing 104. Morespecifically, spring 126 and ball carrier 128, along with additionalcomponents washer 130, seal 132, wave spring 134, bearing tube 136,sleeve keeper 138 and O-ring 140 are assembled within collet housing104. Coupling assembly 102 also includes hex closure sleeve 142, spring144, rotor shaft 146, and ball bearings 148 retained in openings 147 inthe rotor shaft by retaining ring 150. This internal assembly iscompleted by bearing 152 and lock ring 154. Coupling assembly 102 isshown in cross-section in its assembled configuration in FIGS. 5A and5B.

[0096] With reference to FIG. 3, it will be understood that proximalportion 156 is received within an internal portion of motor housingexterior cover 81 and firmly affixed thereto by any known attachmentmechanism. Rotor shaft 146 engages a portion of rotor shaft 92 of motor80 to provide a power coupling there between. Rotor shaft 146 includesan internal socket 160 adapted to receive the proximal portion ofdissection tool 18. Internal socket includes an alignment pin 162surrounded by socket end wall 164. Axially disposed adjacent the distalend of alignment pin 162 is an internal shoulder 166. Although thepreferred embodiment illustrated in FIG. 3 shows alignment pin 162 asbeing integral with rotor shaft 146, it is contemplated that theseelements may be separate components coupled to each other during theassembly process.

[0097] Referring now to FIGS. 6A-6C, there is shown a dissection tool inaccordance with the present invention. Dissection tool 18 includes anelongated shaft 19, a dissection head 20 and a connection end 21.Connection end 21 includes a plurality of driving surfaces 182. In thepreferred embodiment shown in FIG. 6A, driving surfaces 182 aresubstantially planar and extend in substantially parallel alignment withthe longitudal axis of dissection tool 18. As shown in the cross-sectionof FIG. 6C, driving surfaces 182 are formed in a substantially hexagonalpattern to define driving corners 183 between each driving surface.Alternative cross-sections of dissection tool 18 adjacent connection end21 may include eight driving surfaces 192, four driving surfaces 194 orthree driving surfaces 196 to form the octagonal, square, or triangularcross-sectional configurations shown in FIGS. 7A, 7B and 7C,respectively. Connection end 21 further includes an alignment bore 180centered on and extending at least partially along longitudal axis ofdissection tool 18. In a preferred aspect, the distal end of alignmentbore 180 is in substantial alignment with the distal portion of drivingsurfaces 182. Adjacent to proximal end of connection end 21 are taperedsurfaces 186 transitioning between flat end 188 and drive surfaces 182.

[0098] Referring to FIG. 5A, coupling 102 is shown in the unlockedposition. Ball 106 is positioned in helical groove 105 in the proximalposition. Ball 106 rides in ball carrier 128 and is moved by ball 106 tothe proximal position shown in FIG. 5A. In the proximal position, ballcarrier 128 urges closure sleeve 142 to compress spring 126 and permitsspring 144 to expand to a relaxed position. In the unlocked proximalposition, closure sleeve 142 is moved away from locking ball 148permitting it to move at least partially out of hole 147. However,o-ring 140 tends to urge locking ball 148 into hole 147. Thisarrangement provides positive positioning of locking ball 148 in hole147 and into channel 158 such that upon insertion of coupling end 21into socket 160, locking ball 148 will snap into annular groove 184providing tactile feedback to the user that coupling end 21 is properlypositioned in coupling assembly 102.

[0099] Dissection tool 18 is advanced within channel 158 until couplingend 21 is disposed adjacent alignment pin 162. Co-axial with alignmentpin 162, socket 160 has a plurality of drive surfaces 161. In thepreferred embodiment shown, drive socket 160 has six drive surfaces 161arranged in a hexagonal pattern substantially matching the hexagonalpattern of FIG. 6A. However, in a preferred aspect of the inventionshown in FIG. 6D, drive surfaces 161 are convexly shaped such that theytend to engage a central portion of surface 182 spaced from comer 183.In some applications, rotation speeds are approximately 70,000 rpm suchthat good connection between surfaces 161 and surface 182 is necessary.As dissection tool 18 is advanced, tapered surfaces 186 may engageinternal shoulder 166 at the beginning of the drive surfaces 161 toestablish initial axial alignment. In a preferred aspect, suchengagement between tapered surfaces 186 and internal shoulder 166 alsotends to rotationally align planar driving surfaces 182 with planardriving surfaces 161. It is contemplated that this feature may be astraight chamfer as opposed to the hex chamfer shown in FIG. 6A. Thus,tool coupling end 21 includes a mechanism for rotational alignment. Asthe tool is further advanced into socket 160, tapered tip 163 onalignment pin 162 may enter alignment bore 180 and engage a portion ofthe alignment bore to adjust the longitudinal axis of tool shaft 19 intosubstantial alignment with the longitudinal axis of rotor shaft 146. Ina preferred aspect there is a close tolerance between the internaldiameter of the alignment bore 180 and the external diameter of thealignment pin 162 such that as the pin advances in the bore there issubstantial parallel alignment between the cylindrical surfaces of thepin and bore, with the resulting substantial axial alignment between thelongitudinal axis of the tool shaft 19 and longitudinal axis of therotor shaft 146.

[0100] After dissection tool coupling end 21 has been properlypositioned in coupling assembly 102, proximal Double D collet 114 may berotated with respect to the other elements of the housing to urge ball106 and ball carrier 128 to their distal, locking position shown in FIG.5B. FIG. 5B shows a cross-section of coupling assembly 102 with proximalDouble D collet 114 and balls 106 shown in the position of FIG. 5A andthe remaining elements rotated approximately 90° with respect to theorientation shown in FIG. 5A. It will be understood that in operation ofthe illustrated preferred embodiment, proximal Double D collet 114 andballs 106 are moved while the other element remain stationary. As ballcarrier 128 advances distally, spring 140 is compressed and spring 126is allowed to expand. As spring 126 expands, it urges closure sleeve 142distally. Internal taper surface 143 of closure sleeve 142 engageslocking ball 148 and urges it into locking engagement with annulargroove 184. Closure sleeve 142 continues to advance over locking ball148 to securely hold locking ball 148 in the annular groove 184, therebyinhibiting movement of dissection tool 18 along the longitudinal axis.In the preferred embodiment illustrated, annular groove 184 is uniformlyconcave in longitudinal cross-section and does not actively participatein the transmission of rotational force to tool shaft 19. However, it iscontemplated that annular groove may include surface configurationsadapted to receive rotational force and may thereby cooperate in drivingtool shaft 19.

[0101] As previously described, attachment housing 16 includes aninternal cavity 63 having a configuration substantially matching theexternal configuration of coupling assembly 102. More specifically, in apreferred aspect the proximal portion of internal cavity 63 includesdriving flat 64 (FIG. 3) substantially matching flat 56 and opposingflat (not shown) and internal cylindrical portions (not shown)substantially matching cylindrical portion 58 and the opposingcylindrical portion (not shown) on the coupling assembly. Similarly,internal cavity 63 includes an internal cylindrical portion 66 disposedadjacent flat 52 and cylindrical portion 54. Thus, as the attachmenthousing 16 is advanced over distal portion 51, driving flat 64 initiallyaligns with and guides over flat 52. When positioned in the operationposition shown in FIG. 3, driving flat 64 is positioned over flat 56 anddoes not extend to flat 52. In use, as the attachment housing 16 isrotated with respect to motor housing 12, driving flat 64 cooperateswith flat 56 to rotate proximal Double D collet 114 to the lockedposition while internal cylindrical portion 66 rotates over flat 52. Itwill be understood that as flat 64 rotates past cylindrical portion 54,attachment housing 16 becomes locked to motor housing 12. As shown inFIG. 3, proximal shoulder 60 of cylindrical portion 54 engages distalshoulder 62 of driving flat 64. It will be understood that the singlepartial rotation of the attachment housing 16 about the longitudinalaxis of motor housing 12 positively locks both dissection tool 18 tocoupling assembly 102 and attachment housing 16 to motor housing 12.

[0102] Referring now to FIGS. 8A through 8D, a further embodiment of acoupling assembly and dissection tool according to the present inventionare illustrated. Coupling assembly 202 has a number of attributes incommon with the embodiment shown in FIGS. 3 through 5B and may cooperatewith the assembly housing 16 and motor housing 12 in the mannerpreviously described. Coupling assembly 202 includes collet housing 204having slot 205 and holes 207. Ball bearings 206 and alignment balls 208are configured to at least partially engage slot 205 and holes 207,respectively. As with the earlier described embodiment, Double D sleeve214 is provided to engage attachment housing 16 and move the couplingassembly between the unlocked and locked positions.

[0103] Coupling assembly 202 includes a number of components internallypositioned within collet housing 204. Such internal components includespring 244, anterior spring shim 247, ball carrier 248, closure sleeve230 and spring 226. Disposed within closure sleeve 230 is the rotorshaft 260 with a non-integral alignment pin 262. A pair of bearings 250and 252 are provided to support rotor shaft 260.

[0104] Referring now to FIG. 8B, tool shaft 296, rotor shaft 260 andalignment pin 262 are shown in partial cross-sectional perspective view.Tool shaft 296 is shown having a coupling end with an alignment channel297 extending along and in substantial alignment with the longitudinalaxis L2 of the tool shaft. The coupling end also includes annular groove298 and annular shoulder 299. Rotor shaft 260 includes four flexiblegripping fingers 265 spaced from each other by openings 268 and integralwith uninterrupted cylindrical portion 273. Rotor shaft 260 includes aninternal bore 261 adapted to receive alignment pin 262 with projection264. Alignment pin 262 may be joined to rotor shaft 260 via a mechanicalpin connection transverse to the longitudinal axis or by any othersuitable connection. Each gripping finger 265 includes an internalleading taper surface 267 adjacent the distal end. Drive surface 266 isdisposed adjacent to taper surface 267 followed by annular internalgroove 269 on each gripping finger 265. The exterior of each grippingfinger 265 includes annular ridge 270, external annular recess 272,taper section 274 and second ridge 276.

[0105] Referring to FIG. 8C, the coupling assembly 202 is shown in theopen position. Spring 226 is compressed by proximal movement of closuresleeve 230 resulting from the movement of ball carrier 248 against rib232. With the closure sleeve 230 in the proximal position, distal spring244 is in an expanded condition. Closure sleeve 230 includes internalannular rings 240 and 242. In the open position, annular rings 240 and242 are positioned over annular recess 272 and reduced diameter portion278, respectively, of the rotor shaft. In the unlocked position, fingers265 are free to splay to permit passage of the enlarged projectingshoulder 299 of tool shaft 296. Internal surface 238 on closure sleeve230 limits the amount of splay of fingers 265. Reduced diameter portion278 provides an area of strain relief and flexibility to permit theoutward movement of fingers 265. As previously described, alignmentprojection 262 cooperates with alignment channel 297 on tool shaft 296to provide axial alignment of the tool shaft and the rotor shaft alonglongitudinal axis L2.

[0106] Referring to FIG. 8D, coupling assembly 202 is shown in thelocked position around tool shaft 296. As previously described, in apreferred embodiment the attachment assembly 16 is rotated to moveDouble D collet 214 and drive ball 206 along slot 205. This movementmoves ball carrier 248 distally to compress spring 244. Spring 226 thenacts on rib 232 to move closure sleeve 230 distally over rotor shaft260. As closure sleeve 230 advances distally, taper surface 236 engagesshoulder 241 of ridge 270 while taper surface 274 engages ridge 276,each acting to close driving surfaces 266 on annular groove 298. Oncethe locking diameter of rotor shaft is achieved, closure sleeve 230continues distally to bring internal annular rings 240 and 242 intoengagement with ridges 270 and 276 to thereby lock rotor shaft 260 inthe locking position. Engagement of groove 269 and shoulder 299 preventwithdrawal of the tool shaft from the coupling assembly. It will beunderstood that alignment projection 264 maintains longitudinalalignment of the tool shaft during the closing of the locking fingersthereby assuring that proper axial alignment is achieved when thecoupling assembly is locked.

[0107] Referring now to FIGS. 9A and 9B, a coupling assembly 302according to another aspect of the present invention is shown. As withpreviously described preferred embodiments, coupling assembly 302utilizes a ball 310 and ball carrier 308 in a spring biased relationshipbetween springs 304 and 306 to move the coupling closure sleeve 312between the unlocked and locked positions. While the foregoing has beenshown in the preferred embodiments, such is provided for the purpose ofillustration it being understood that alternative mechanisms forcontrolling the coupling assembly between the locked and unlockedpositions is contemplated. Rotor shaft 315 includes an internal boreadapted to receive alignment shaft 330 with projecting alignment pin332. In the present embodiment, alignment shaft 330 includes atransverse bore 334 and a pin 336 extending from rotor shaft 315 intothe bore to join the alignment shaft and rotor shaft. Rotor shaft 315includes a plurality of apertures 316 adjacent the distal end. Aplurality of grippers 350 are attached to rotor shaft 315. Each gripperincludes a driving face 352 extending through aperture 316 andselectively into channel 320. Distal end 322 of rotor shaft includes anexternal flange and a plurality of detents 324 in the flange. Thedetents receive a portion of each gripper 350. Further, the bottom ofeach detent includes a rounded projection 324. Each gripper 350 includesa concave detent 354 riding over rounded projection 318. It will beunderstood that grippers 350 may pivot about the engagement betweenprojection 318 and detent 354. Grippers 350 also include an enlarged end356 opposite driving face 352. Tension band 360, such as an o-ring orspiral band, is disposed proximally of the pivot point at detent 354 tobias driving face 352 to extend through aperture 316 an into channel320. It will be understood that the bias force of o-ring 360 may berelatively easily overcome, with closure sleeve 312 moved proximallyinto the unlocked position (not shown), by inserting a tool shaft andthat driving face 352 will snap against the corresponding drivingsurface on the tool shaft to provide a tactile feedback to the user thatthe tool shaft is properly positioned in the coupling assembly.

[0108] In use, a tool shaft coupling end is inserted into channel 320until it is seated in the coupling assembly with alignment pin 332providing proper longitudinal alignment. Closure sleeve 312 may then beadvanced distally such that internal taper 314 acts against grippers350. As rotational force is applied to rotor shaft 315 the centrifugalforce acting on enlarged end 356 will be transmitted by pivot aboutprojection 324 to increase the compressive force of driving faces 352against the tool shaft. As the rotational speed of rotor shaft 315 isincreased, the compressive force of driving faces 352 against the toolshaft will have a corresponding increase.

[0109] Referring to FIGS. 10A through 10C, a series of tool shaftcoupling configurations are shown. Dissection tool shaft 410 has acoupling configuration 412 adapted to be engaged by driving members of acoupling assembly. Dissection tool 410 has a proximal end 414, adjacenttaper surface 416 extending to cylindrical portion 420. A plurality ofdrive surfaces 422 are formed adjacent the proximal end. In theembodiment shown in FIG. 10A, there are six planar drive surfaces 422.Each drive surface 422 includes corners 424 and 426 extendingsubstantially parallel to longitudinal axis L3. Further, each drivesurface 422 includes a pair non-orthogonal drive shoulders 428 and 430extending substantially parallel to each other and at a non-orthogonalangle with respect to longitudinal axis L3. It will be appreciated thatdriving members in many applications often strip or round drivingcorners such that torque can no longer be transmitted. As shown in FIG.10A, the distance D3 between adjacent drive faces represents the amountof material that would need to be deformed or removed to permit adriving member to jump to the next drive surface. In contrast, with thenon-orthogonal drive shoulders 428 and 430, material along the distanceD4, approximately ⅙ of the circumference of cylindrical portion 420,would have to be deformed or removed to permit a driving member to jumpto the next drive surface. In other words, the driving surfaceconfiguration includes a structures to inhibit stripping or jumpingalong the entire transverse width of the driving surface. Additionally,the driving member will at least partially drive against shoulder 428generating both a rotational force vector and a longitudinal forcevector tending to force dissection tool 410 into the collet assembly. Itwill be appreciated that a surface 422 configured as illustratedaccomplishes both a driving function and a holding function when used ina mating collet assembly.

[0110] Referring to FIG. 10B, a dissection tool 440 with drive end 442and cylindrical body 444 is shown. Drive end 442 includes a plurality ofdrive surfaces 446 extending around the circumference and within thediameter of cylindrical body 444. Each drive surface 446 includes drivecorners 448 and 450 extending substantially parallel to longitudinalaxis L4. Further, each drive surface 446 includes a pair of opposednon-orthogonal drive shoulders 428 and 430 extending substantiallynon-parallel to each other and at a non-orthogonal angle with respect tolongitudinal axis L4. As with the previously described embodiment, thedriving surfaces 446 increase resistance to stripping and increase thedriving surface area for mating with a corresponding driving member.Further, when the driving member (not shown) drives against shoulder 452it tends to hold the tool in the collet.

[0111]FIG. 10C shows still a further embodiment of a dissection tool 460having non-orthogonally oriented driving surfaces. Driving surface 466is a non-planar, substantially elliptical surface adapted to receive aportion of a spherical driving member. Driving surface 466 is formed byimpinging upon the cylindrical surface 464 with a ball end mill (notshown) oriented at non-perpendicular angle with respect to longitudinalaxis L5. In a preferred embodiment the angle of incidence of the ballend mill is about 15° with respect to the transverse axis of dissectiontool 460. As previously described with respect to the embodiments ofFIGS. 10A and 10B, spherical driving members disposed in the ellipticalsurfaces 466 may tend to apply force or travel at least partially alongthe axis L6 rather than purely transverse to the longitudinal axis L6 tothereby increase the driving surface area and hold the tool in thecollet assembly.

[0112] Referring to FIGS. 11A-11D, a surgical instrument for thedissection of bone and other tissue constructed in accordance with theteachings of another preferred embodiment of the present invention isillustrated and generally identified at reference numeral 1010. Thesurgical instrument 1010 is illustrated to generally include adissection tool 1012 and a quick release coupling arrangement 1014 forengaging the dissection tool 1012. The teachings of the illustratedpreferred embodiment of the present invention are primarily directed tofeatures of the dissection tool 1012 and the quick release couplingarrangement 1014 which cooperate to center and retain the dissectiontool 1012 with respect to the surgical instrument 1010. Additionalfeatures of the surgical instrument 1010 are described in U.S. Pat. No.5,505,737 which is hereby incorporated by reference.

[0113] The dissection tool 1012 of the surgical instrument 1010 includesa substantially cylindrical shaft having a distal end 1016 and aproximal end 1018. The distal end 1016 of the dissection tool 1012includes a cutting element 1020, while the proximal end 1018 defines acentrally located cylindrical bore 1022. As illustrated, the bore 1022distally extends only partially along a central axis 1024 of thedissection tool 1012. Alternatively, the bore 1022 may distally extendsubstantially along the central axis 1024. The length of the bore 1022is limited only by applications utilizing a closed end cutting element1020, as illustrated in FIG. 11A. In a manner to be discussed below, thebore 1022 cooperates with a centrally located pin 1021 in the spindle ofthe surgical instrument 1010 so as to center the dissection tool 1012within the surgical instrument 1010 along the longitudinal axis. In apreferred aspect, pin 1021 is substantially co-axial and co-terminuswith locking member 1040. It will be understood that the couplingmechanism also prevents the insertion of a dissection tool not designfor use with the surgical tool 1010 from being operatively engaged withthe surgical tool 1010.

[0114] In the embodiment illustrated in FIGS. 11A-11D, the dissectiontool 1012 further includes a cap 1026 formed of a first material whichis secured to the remainder of the dissection tool 1012. In oneparticular application, the cap 1026 is formed of stainless steel, suchas 440 stainless steel, and the remainder 1029 of the dissection tool1012 is formed of tool steel. In certain applications, it may bedesirable to injection mold the cap 1026 from plastic.

[0115] Such a dual material construction of the dissection tool 1012permits the distal end 1016 of the dissection tool 1012 to be made of aharder material to facilitate the cutting action of the dissection tool1012, while the proximal end 1018 can be constructed of a softermaterial that is easier to machine so as to form the bore 1022. The cap1026 defines a generally cylindrical female opening 1028 which receivesa male extension 1030 of the dissection tool 1012. Those skilled in theart will readily appreciate that materials other than that specificallyidentified can be incorporated. Alternatively, the dissection tool 1012can be unitarily constructed of a single material. Further, cap 1026 maybe removably coupled to dissection tool 1012. In this type ofembodiment, cap 1026 may act as an adaptor to permit suitable toolshaving alternative proximal configurations to be used in the coupling.

[0116] The surgical instrument 1010 is illustrated to further include aspindle 1034 which engages and drives the dissection tool 1012 about theaxis of the spindle 1034, and is driven by a motor portion 1035 of thesurgical instrument 1010. The distal end of the spindle 1034 defines acylindrical cavity 1036 for receiving the proximal end 1018 of thedissection tool 1012. While in the embodiment illustrated, the spindle1034 is illustrated as a unitary member, a separate attachment member(not shown) may be used to define the cavity 1036 for receiving thedissection tool 1012 which in turn is secured to the spindle 1034.

[0117] The quick release coupling arrangement 1014 of the surgicalinstrument 1010 is generally illustrated to include a sleeve 1038 andgrippers or locking members 1040. In the embodiment illustrated, thesurgical instrument 1010 is shown to include a three locking members1040. The shape of each locking member 1040 is generally in the form ofa cylindrical section having a convexly shaped cross-sectional exteriorsurface and a generally flat cross-sectional inner surface. The innersurface of the locking member 1040 is operable to engage a reduceddiameter portion 1044, while the outer surface of the locking member1040 is able to engage the sleeve 1038. Each of the locking members 1040are disposed within a radially extending aperture 1042 formed in thespindle 1034 and intersecting the cavity 1036. The locking members 1040are positioned and sized to be received within a reduced diameterportion 1044 of the dissection tool 1012 when the dissection tool 1012is fully inserted into the cavity 1036 as shown in FIG. 11A and FIG.11B.

[0118] The sleeve 1038 is generally tubular in shape and includes acentral aperture 1046 for receiving the spindle 1034. The sleeve 1038 ismovable axially along the spindle 1034 between a first position and asecond position. In the first position shown in FIG. 11B, the sleeve1038 maintains engagement of the locking members 1040 with the reduceddiameter portion 1044 of the dissection tool 1012 thereby bothpreventing (1) inadvertent withdrawal of the dissection tool 1012 fromthe surgical instrument 1010 and (2) rotatably coupling the dissectiontool 1012 with the spindle 1034. In the second position (not shown), thesleeve 1038 is shifted proximally (to the right as shown in FIG. 11B) toallow the locking members 1040 to be displaced radially from the reduceddiameter portion 1044 of the dissection tool 1012. In this secondposition of the sleeve 1038, the dissection tool 1012 maybe withdrawnfrom the cavity 1036 for quick and easy replacement.

[0119] The surgical instrument 1010 further includes a biasing mechanismfor normally biasing the sleeve 1038 to its first position. In theembodiment shown, the biasing mechanism includes a coil spring 1047surrounding a portion of the spindle 1034 which places a distallybiasing force on the sleeve 1038. Accordingly, the sleeve 1038 is biasedby the coil spring 1047 in such a manner as to cause the locking members1040 to engage the reduced diameter portion 1044.

[0120] To facilitate movement of the sleeve 1038 over the lockingmembers 1040, the sleeve 1038 includes a tapered section 1049. Thetapered portion 1049 is located at the distal end of the sleeve 1038 andis oriented so that the inner surface of the sleeve 1038 defined by thetapered portion 1049 has increasing diameter in the region adjacent tothe locking members 1040. Accordingly, as the sleeve 1038 movesdistally, the tapered portion 1049 is able to slide against the outersurface of the locking members 1040 and progressively force the lockingmembers 1040 against the reduced diameter portion 1044 of the dissectiontool 1012.

[0121] The surgical instrument 1010 further includes a plug 1048 thatextends from the spindle 1034 into the cavity 1036. Plug 1048 includesan axially aligned pin 1021 extending distally and having a reduceddiameter. The plug 1048 further includes a shoulder adjacent pin 1021and extending transverse to the longitudinal axis. When the dissectiontool 1012 is fully inserted into the cavity 1036, the pin 1021 extendsinto the bore 1022 of the dissection tool 1012 thereby ensuring properalignment of the axis 1024 of the dissection tool 1012 with a rotationaxis of the spindle 1034. Additionally, proximal end 1018 may abuttinglyengage the shoulder to ensure that reduced diameter portion 1044 isaligned with locking members 1040. The pin 1048 is secured to thespindle 1034 within an aperture 1050 defined in the rotary driveshaft1034 through an interference fit. To improve the tactile feel receivedby the user of the surgical instrument 1010 during the installation ofthe dissection tool 1012 into the spindle 1034, a split spring ring orO-ring 1051 may be incorporated as shown in FIG. 11B. The tactilecomponent 1051 maintains the locking members 1040 in a seated, butmovable position. The combined spring action of the locking members 1040and the tactile component 1051 provide feedback to the user when theflange on the dissection tool 1052 passes the locking members 1040.

[0122] With reference to FIG. 12, a surgical instrument 1310 for thedissection of bone and other tissue according to be teachings of anotherpreferred embodiment of the present invention is illustrated. Thesurgical instrument 1310 according to the fourth preferred embodiment ofthe present invention is similar to the surgical instrument 1010. Inthis regard, a dissection tool 1312 is able to be secured by a quickrelease coupling arrangement 1314 by inserting the proximal end 1318 ofthe dissection tool into the cavity 1336. The dissection tool 1312further includes a slot 1364, having planar side walls, which extendsproximally into the dissection tool 1312 approximately same distance hasthe pin 1048 of the surgical instrument 1010 shown in FIG. 1B. The slot1364 is able to receive an insert 1366 which is located at the proximalend of the cavity 1336. An O-ring 1351 is incorporated between theinsert 1366 and the cylindrical aperture 1350. It will be appreciatedthat slot 1364 may cooperate with insert 1366 to transmit torque fromthe motor to dissection tool 1312.

[0123] Turning to FIGS. 13A-13C, a surgical instrument 1410 for thedissection of bone and other tissue according to the teachings ofanother preferred embodiment of the present invention is illustrated.The surgical instrument 1410 according to another preferred embodimentof the present invention shares various common elements with thesurgical instrument 1010 of a preferred embodiment of the presentinvention. For this reason, like reference numerals are used to identifysubstantially identical elements. The surgical instrument 1410 differsfrom the surgical instrument 1010 in that a dissection tool 1412 of thesurgical instrument 1410 is able to be intra-operatively telescopedbetween a retracted position (as shown in FIG. 13B) and a fully extendedposition (as shown in FIG. 13C).

[0124] The proximal end of the dissection tool 1412 is formed to includea plurality of reduced diameter portions 1044. In the embodimentillustrated, the dissection tool 1412 is shown to include five suchreduced diameter portions 1044. However, those skilled in the art willreadily appreciate that a greater number or a lesser number of reduceddiameter portions 1044 may be incorporated within the scope of thepresent invention.

[0125] The proximal end of the dissection tool 1412 further includes acentrally located cylindrical bore 1022 extending co-axially andsubstantially co-terminus with reduce diameter portions 1044. As withthe first preferred embodiment, the bore 1022 cooperates with a pin 1048that extends from the spindle 1034 into the cavity 1036. The pin 1048extends into the bore 1022 of the dissection tool 1412 so as to ensureproper alignment of an axis of the dissection tool 1412 with arotational axis of the spindle 1034.

[0126] Each of the reduced diameter portions 1044 is adapted toselectively receive the locking members 1040. In FIG. 13B, the lockingmembers 1040 are shown engaging a distal-most reduced diameter portion1044. In FIG. 13C, the locking members 1040 are shown engaging aproximal-most reduced diameter portion 1044. The locking members 1040may similarly engage the intermediate reduced diameter portions 1044. Inthis manner, a surgeon can intra-operatively telescope the dissectiontool 1412 when the sleeve 1038 is retracted against the bias of the coilspring 1047. In the embodiment illustrated, the reduced diameterportions 1044 effectively define five positive positions for telescopingof the dissection tool 1412 relative to the sleeve 1038. In thisapplication, the reduced diameter portions 1044 each have a length ofapproximately 0.081 inches and lands between adjacent reduced diameterportions 1044 each have a length of approximately 0.068 inches. Furtherin this particular application, the dissection tool 1412 can telescopeapproximately 0.5 inches between the fully retracted position and thefully extended position.

[0127] With reference to FIG. 14, a dissection tool 1510 in accordancewith the teachings of another preferred embodiment of the presentinvention is illustrated. It will be understood that the dissection tool1510 is adapted to be used with the surgical tool 1410 of the fifthpreferred embodiment of the present invention, for example. Thedissection tool 1510 differs from the dissection tool 1412 in that itincludes a single, elongated reduced diameter portion 1512. The lockingmembers 1040 can engage the reduced diameter portion 1412 anywhere alongits length. In this manner, the dissection tool 1510 can be infinitelyadjusted telescopically relative to the sleeve 1038 between a fullyretracted position and a fully extended position.

[0128] With reference now to FIGS. 15A-15D, a dissection tool 1610according to the teachings of still another preferred embodiment of thepresent invention is illustrated. The dissection tool 1610 is intendedfor use, for example, in the surgical tool 1010 of FIG. 11A. Dissectiontool 1610 includes an alignment bore 1618 with a chamfer 1620 disposedadjacent the proximal end. The dissection tool 1610 differs from thedissection tool 1012 in that a reduced diameter portion 1614 is definedby a plurality of facets or sides 1616. In all other respects, it willbe understood that the dissection tool 1610 and 1612 are substantiallyidentical.

[0129] In the embodiment illustrated, the reduced diameter portion 1016is illustrated to include nine (9) sides 1616. The sides 1616 areequally spaced about the outer diameter of the reduced diameter portion1614. The sides 1616 are selectively engaged by the locking members 1040depending on the orientation of the dissection tool 1610.

[0130] It will be understood that the dissection tool 1610 may include agreater or lesser number of sides 1616 within the scope of the presentinvention. Preferably, the number of sides 1616 is equally divisible bythe number of locking members 1040. In the embodiment illustrated, thenine sides 1616 are equally divisible by the three locking members 1040.In this manner, the three locking members 1040, which are equally spacedabout the reduced diameter portion 1614, each engage one of the sides616 of reduced diameter portion 1614.

[0131] A cross-sectional view similar to FIG. 15D is shown in FIG. 16and illustrates a dissection tool 1710 in accordance with an eighthpreferred embodiment of the present invention. The dissection tool 1710includes a reduced diameter portion 1714 having a plurality of sides1716 and an alignment bore 1718. In this example, the reduced diameterportion is defined by twelve (12) sides 1716. This is but a secondexample of a reduced diameter portion defined by a plurality of sideswhich is equally divisible by the number of locking members. Explainingfurther, if the surgical tool 1010 were constructed to include four (4)locking member 1040 equally spaced about a dissection tool, a reduceddiameter portion of the dissection tool may include 4, 8, 12 or a highermultiple of four sides.

[0132] Turning finally to FIGS. 17A-17E, a surgical tool 1810constructed in accordance with the teachings of another preferredembodiment of the present invention is illustrated. The surgicalinstrument is illustrated to generally include a dissection tool 1812, ahousing 1814, and a tube assembly 1816. In the embodiment illustrated,the proximal end of the dissection tool 1812 is shown to include aplurality of facets or sides 1817 which taper toward a surface 1818. Theproximal end further includes a plurality of recesses 1820. In oneparticular application, the dissection tool 1812 has a diameter ofapproximately 0.046 inches and is particularly suited for minimallyinvasive surgeries, including but not limited to neurosurgery.

[0133] The housing 1814 rotatably supports an input or drive shaft 1822with at least one bearing 1824. The housing 1814 forwardly extends todefine a generally cylindrical recess 1826 for receiving the tubeassembly 1816. The input shaft 1822 partially extends into thecylindrical recess 1826 and at its distal end defines a pair of flexurearms 1828. In a manner to be addressed more fully below, the flexurearms 1828 of the input shaft 1822 cooperates to selectively retain thedissection tool 1812.

[0134] A coupling arrangement 1830 for selectively securing thedissection tool 1812 to the input shaft 1822 is carried by the distalend of the input shaft 1822. The coupling arrangement 1830 isillustrated to include a closure member 1832 for selectively moving theflexure arms 1828 between an open position for permitting insertion andremoval of the dissection tool 1812 in a closed position for securingthe dissection tool 1812 to the input shaft 1822. The closure member1832 is generally cylindrical in shape having a first portion 1833 and asecond portion 1834, the inner diameter of the second portion 1834 beinggreater than the inner diameter of the first portion 1833. The closuremember 1832 is linearly movable relative to the input shaft 1822 betweena clamped position and an unclamped position. The clamped position isshown in the cross-sectional views of FIGS. 17A and 17B.

[0135] The closure member 1832 is normally biased to its clampedposition by a coil spring 1838. When the closure member 1832 is in theclamped position, the flexure arms 1828 of the input shaft 1822 aredisposed within the smaller diameter portion 1833 and the flexure arms1828 clampingly engage the proximal end of the dissection tool 1812.When the closure member 1832 is translated against the bias of thespring 1838, in a manner to be discussed below, a portion of the flexurearms 1828 extend into the larger diameter portion 1834 and are therebypermitted to spread apart for permitting removal or insertion of thedissection tool 1812.

[0136] The tube assembly 1816 is illustrated to include a first or outertube member 1840 and a second or inner tube member 1842. The inner tubemember 1840 carries a plurality of bearings 1844 for rotatablysupporting the dissection tool 1812. In the embodiment illustrated, theplurality of bearings includes three bearings 1844. The outer tubemember 1840 is sized to be received within the cylindrical recess 1826defined by the housing 1814. However, a greater or lesser number ofbearings may be employed for alternate applications. Bearing guidemembers 1846 are disposed on either side of the plurality of bearings1844 and function to facilitate insertion of the dissection tool 1812.

[0137] A bearing 1848 is carried by the outer tube member 1840 and iscaptured between an inwardly extending radial flange 1850 of the outertube member 1840 and a proximal end of the inner tube member 1842. Thebearing 1848 abuts a guide member 1852 which is press fit into a distalend of the closure member 1832. In response to translation of the tubeassembly 1816, the bearing 1848 pushes on the guide member 1852 which inturn translates the closure member 1832 from its clamped position (shownin FIG. 17B) to its unclamped position (not shown) against the bias ofthe spring 1838.

[0138] A lock nut 1854 circumferentially surrounds the distal end of thehousing 1814 and functions to secure the housing 1814 to the tubeassembly 1816. In this regard, the lock nut 1854 is interconnected tothe housing 1018 through a plurality of threads 1856. The lock nut 1854and the housing 1814 include cooperating tapered surfaces 1858 and 1860,respectively. Through these tapered surfaces 1858 and 1860, tighteningof the lock nut 1854 causes the housing 1814 to grip the tube assembly1816 and thereby arrest relative movement therebetween. Correspondingly,untightening of the lock nut 1854 permits withdrawal and insertion ofthe tube assembly 1816.

[0139] As with the surgical tool 1410, the surgical tool 1810 permits asurgeon to intra-operatively adjust the exposed length of the dissectiontool 1812.

[0140] With reference to FIGS. 18A or 18B, the surgical instrument fordissection of bone and other tissue in accordance with the teachings ofa further preferred embodiment is generally identified at referencenumeral 1110. FIG. 18A is a cross-sectional view of a portion of thesurgical instrument 1110 similar to the cross-sectional view of FIG.11B. FIG. 18B is a perspective view of a portion dissection tool 1112.

[0141] With the exception of the proximal end of the dissection tool1112 that is used to secure the dissection tool 1112 to the surgicalinstrument 1110, it will be understood that the dissection tool 1112 isotherwise substantially identical to the dissection tool 1012. As shownin FIG. 18B, the proximal end of the dissection tool 1112 includes aplurality of facets or sides 1114 which taper toward a point. In theembodiment, the dissection tool 1112 includes four tapered sides 1114.However, those skilled in the art will readily appreciate that anynumber of tapered sides 1114 may be incorporated within the scope of thepresent invention. In addition, the dissection tool 1112 furtherincludes a reduced diameter section 1116 which is used to receive aplurality of locking balls 1124 described below.

[0142] The dissection tool 1112 is received within a cylindricalaperture 1120 defined the spindle 1122 of the surgical instrument 1110.A first pair of locking balls 1124 are disposed within radiallyextending apertures 1126 provided in the spindle 1122. The radiallyextending apertures 1126 intersect the cylindrical cavity 1120 so as toallow the locking balls 1124 to selectively engage the reduced diametersection 1116 of the dissection tool 1112. A pair of drive balls 1128 aresimilarly located in a corresponding pair of radially extendingapertures 1130 defined in the spindle 1122 which intersects thegenerally cylindrical aperture 1120. Upon full insertion of thedissection tool 1112 into the generally cylindrical cavity 1120, thepair of drive balls 1128 engage two of the tapered sides 1114 of thedissection tool 1112. The drive balls 1128 engage the dissection tool1112 to rotatably interconnect the spindle 1122 and the dissection tool1112. In addition, the engagement of tapered sides 1114 and drive balls1128 function to center the dissection tool 1112 within the generallycylindrical aperture 1120 and in alignment with the longitudinal axis.

[0143] The surgical instrument 1110 is further illustrated to include agenerally tubular sleeve 1138 surrounding the spindle 1122 in a mannersimilar to the sleeve 1038 of the first preferred embodiment. The sleeve1138 is movable between a first position (shown in FIG. 18A) and asecond position (shifted to the right from that shown in FIG. 18A). Abiasing mechanism such as the coil spring of the first preferredembodiment functions to bias the sleeve 1138 to its first position. Toimprove the tactile feel received by the user of the surgical instrument1110 during engagement between the sleeve 1038 and the locking balls1124, a split ring or an O-ring may be provided in a tapered portion ofthe sleeve 1138.

[0144] When the sleeve 1138 is in its first position, the locking balls1124 are forced into engagement with the reduced diameter section 1116of the dissection tool 1112 to thereby inhibit inadvertent withdrawal ofthe dissection tool 1112 from the generally cylindrical cavity 1120.Further, when the sleeve 1132 is in its first position, the drive balls1128 are securely engaged with the tapered sides 1114 of the dissectiontool 1112 so as to allow the drive balls 1128 to rotate the dissectiontool 1112.

[0145] When the sleeve 1138 is shifted to its second position, thelocking balls 1124 are permitted to radially move within the apertures1126 to thereby allow withdrawal of the dissection tool 1112 from thegenerally cylindrical aperture 1120. Further, in the second position ofthe sleeve 1138, the drive balls 1128 are also aligned with a sphericalgroove 1134 defined on the inner diameter of the sleeve 1138. Thespherical groove 1134 will receive drive balls 1128, preventing themovement of the sleeve to the first position if the user installs adissecting tool that was not designed for use in this instrument.

[0146] With reference to FIGS. 19A and 19B, a surgical instrument 1210for the dissection of bone and other tissue according to the teachingsof a further preferred embodiment of the present invention isillustrated. A dissection tool 1212 is secured to a sleeve 1232 in thesurgical instrument 1210 in a manner similar to the embodiment shown inFIGS. 18A and 18B. In this regard, the dissection tool 1212 includes twotapered sides 1214 at the distal end of the dissection tool 1212, andtwo partially spherical recesses 1216 also at the distal end of thedissection tool 1212. The tapered sides 1214 are used to engage twodrive balls 1228 which are secured in the radially extending recesses1230 located in the spindle 1232 and act to align the dissection tool1212. In addition, the partially spherical recesses 1216 are used toengage two locking balls 1224 which are located in radial extendingapertures 1226 in the spindle 1234. The dissection tool 1212 includes asleeve 1232 which is used to move the locking balls 1224 as well as thedrive balls 1228 in such a manner as to secure or release the dissectiontool 1212 from the surgical instrument 1210 in a manner similar to thatshown in FIG. 18A.

[0147]FIG. 20A and 20B illustrate a dissection tool 2010 according tostill a further aspect of the present invention. Dissection tool 2010includes a cutting end 2012, a shaft 2014 and a power coupling end 2016.The power coupling end 2016 is adapted to mate with a coupling assembly(FIGS. 21A through 23) to transfer rotational force to the cutting end2012. The coupling end 2016 includes a drive area 2018 shown in anexemplary form as six planar sides defining a substantially hexagonaldrive area. Disposed between end 2026 and drive area 2018 is a lockinggroove 2020 having a smaller diameter than the drive area 2018.Immediately adjacent end 2026 is alignment portion 2022 having aconfiguration substantially matching the driving area 2018. In apreferred aspect, although not required with the present invention,alignment portion 2022 also cooperates with a drive socket to transferrotary motion to the tool. It will be appreciated that the hexagonalconfigurations shown for the driving area 2018 and the alignment portion2022 may be modified to utilize any configuration suitable for matingwith a corresponding coupling assembly. Disposed internally to thealignment portion 2022 and the locking groove 2020 is an axial alignmentbore 2024. In the embodiment illustrated in FIG. 20A, the alignment bore2024 extends approximately 0.022 inches within the drive area 2018.However, the alignment bore 2024 may be configured such that it does notextended beyond the drive area 2018.

[0148]FIGS. 21A and 21B illustrate a coupling assembly 2030 inaccordance with another aspect of the present invention. The exteriorsurface of the coupling assembly 2030 includes a first cylindricalmating surface 2032 having a first diameter and a second cylindricalmating surface 2034 having a second smaller diameter adjacent the toolcoupling end 2033. The second cylindrical mating surface 2034 isinterrupted by three planar driving surfaces 2036 adapted for engagementwith a tool for assembling coupling assembly 2030. The remainder of thecoupling end 2033 includes generally conical tapering surface 2038.

[0149] A cross sectional view of the coupling assembly 2030 taken alongline 22-22 is shown in FIGS. 22A and 22B. The majority of the componentsof the coupling assembly 2030 are substantially identical the couplingassemblies previously described in reference to FIGS. 2A through 9B andwill not be further discussed herein. However, the driving socket 2043of the coupling assembly 2030 has been modified in the illustratedembodiment. Referring additionally to FIG. 23, the rotor shaft 2040includes a substantially cylindrical tool receiving aperture 2042 incommunication with the driving socket 2043. The driving socket 2043includes a plurality of driving walls 2044 and 2046. Driving walls 2044and 2046 are separated by a corner 2048. In the illustrated embodiment,the driving walls define a substantially hexagonal driving socket 2043.

[0150] A series of projections 2050 extending from each driving wall2044 line the transition between the substantially cylindricalconfiguration of the tool receiving aperture 2042 and the substantiallyhexagon drive socket 2043. Each projection 2050 extends in substantialalignment with the midline of each driving wall 2044 with opposingplanar walls 2052 and 2054 meeting near the midline to define an apex.The planar walls extend substantially transverse to the longitudinalaxis. Each of the planar walls extends from the apex towards the corners2048 and 2049, respectively. Thus, in the exemplary embodiment theprojection has a generally triangular shape with the apex disposedadjacent tool receiving aperture 2042 and the base adjacent drive socket2043. Further, projection 2050 has an internal surface in substantiallyco-planar alignment with the drive wall 2044. It will be understood thatthe midline of the driving surfaces defines a minimum diameter and thecorners define a maximum diameter for the driving socket. The maximumdiameter in the illustrated embodiment is substantially equal to thediameter of the cylindrical tool receiving aperture. While such featuresmay be formed by many different machining, molding, casting or otherforming method, it is contemplated that the projections may be formed byelectric discharge machining (EDM).

[0151] Rotor shaft 2040 further includes locking balls 2060 extendingthrough apertures in the walls such that a portion of the locking ballmay extend into drive socket 2043. In the preferred embodiment, threelocking balls are used and each aperture is uniformly spaced around thedrive socket and in substantial alignment with a comer between twoadjacent drive walls. As a result, each drive wall has approximately thesame amount of wall space dedicated to the locking balls. Locking balls2060 are biased into the driving socket by o-ring 2066 (FIG. 22B).Further, a locking ring 2080 may be moved to a position co-axially withthe locking balls 2060 to affirmatively hold them in the driving socket.

[0152] A locking pin 2070 with an alignment projection 2072 is retainedby a press fit within rotor shaft 2040 such that the alignment pin isdisposed at least partially co-axially with locking balls 2060. Thealignment projection 2072 is positioned in substantial alignment withthe longitudinal axis of the collet assembly 2030. A conically taperedportion 2074 transitions from the tip to the main body of the alignmentprojection 2072. In a preferred aspect, the diameter of alignmentprojection 2072 is selected in relation to the diameter of the drivesocket 2043 and the diameter of locking balls 2060 such that thealignment projection prevents the locking balls from moving fully intothe drive socket and falling out of the apertures in the rotor shaft2040. Thus, the alignment projection 2072 acts as a locking ballretention device.

[0153] Referring to FIG. 24, the collet assembly 2030 is illustrated inmating engagement with a portion of an attachment assembly 2090 similarto the attachment assembly shown in FIGS. 2A-3. Attachment assembly 2090has an internal chamber 2091 configured to receive a portion of colletassembly 2030. More specifically, internal chamber 2091 includes a firstcylindrical bearing surface 2092 having an internal diameter closelymatching the external diameter of first cylindrical mating surface 2032on the collet assembly. Similarly, internal chamber 2091 includes asecond cylindrical bearing surface 2096 having an internal diameterclosely matching the external diameter of second cylindrical matingsurface 2034. Internal tapered surface 2094 is configured to mate withconical tapering surface 2038. It will be appreciated that whenattachment assembly 2090 is mounted on collet assembly 2030 withsurfaces 2092 and 2096 co-axially disposed adjacent surfaces 2032 and2034, respectively, motion transverse to the longitudinal axis issubstantially prevented. However, rotation of attachment assembly aboutthe longitudinal axis may be performed with the cylindrical bearingsurfaces fully supporting the engagement during rotation. The front andrear points of contact between the closely matched cylindrical surfacesprovides a good fit between the components to inhibit unwantedtransverse movement even if slight axial movement occurs between thecollet assembly and the attachment assembly.

[0154] In use, the tool 2010 is inserted into the collet assembly 2030along the longitudinal axis as shown in FIG. 22A. As coupling end 2016advances, alignment portion 2022 is forced into engagement withprojections 2050. Continued axial force applied on tool 2010 will urgethe corners of alignment portion 2022 into engagement with projections2050. As the corners engage the projections 2050 they will tend tofollow one of the opposing planar walls 2052 or 2054 until the corner ofthe tool coupling end is in substantial alignment with one of thealignment portion 2022 and is in substantial alignment with the corners2048 or 2049 of the driving socket. The hexagonal configuration ofalignment portion 2022 must be in substantial rotational alignment withhexagonal drive socket 2043 to permit further axial movement into thedrive socket. With the projections of the drive socket extending intothe alignment bore, the present invention permits automatic rotationalalignment of the tool shaft coupling end with the driving socket as thetool is axially advanced in the collet assembly.

[0155] As tool coupling end 2016 is advanced into drive socket 2043,alignment portion 2022 urges locking balls 2060 substantially out of thedriving socket and into the apertures provided in the rotor shaft.Further, taper portion 2074 tends to engage a portion of alignment bore2024 to bring the alignment bore and alignment pin into alignment alongthe longitudinal axis. The tool shaft may be further advanced until end2026 engages the locking pin body. In this position, locking groove 2020is positioned adjacent locking balls 2060 which may be received therein.With the biasing O-ring 2066, locking balls 2060 may tend to snap intolocking groove 2020 giving the end user a tactile and audible sensationthat the tool shaft is properly positioned in the collet assembly. Asdescribed with previous embodiments, the attachment assembly may berotated with respect to the collet assembly to thereby axially displacelock ring 2080 over locking balls 2060 to maintain them in a lockedconfiguration extending into the drive socket and affirmatively holdingthe tool from axial movement. The present embodiment illustrates acombination driving socket and tool locking assembly co-axially locatedin the rotor assembly. Further, an alignment pin is also co-axiallylocated with and internal to the locking assembly.

[0156]FIGS. 25A and 25B depict another embodiment of the presentinvention. FIG. 25A shows the motor housing 12 having distal portion 51and hose assembly 14 as previously described with respect to FIGS. 2Athrough 5. The motor 12 includes the coupling assembly 2030 shown inFIGS. 21A through 24. In certain applications, it is desirable to havethe attachment and dissection tool extend at an offset angle withrespect to the motor housing 12. FIG. 25A illustrates an angled adaptor2510 for use with the motor housing 12. The angled adaptor 2510 includesa motor coupling end 2512 adapted for fitting over the distal portion51. As shown in more detail in FIG. 26, the angled adaptor 2510 alsoincludes a tool coupling collet assembly 2516 substantially identical tothe tool collet assembly depicted in FIGS. 21A through 24 disposed undersection 2518. In the illustrated embodiment, an attachment tube 2514 isfixedly coupled to the angled adaptor 2510. The section 2518 may berotated about the angled adaptor 2510 to actuate the tool couplingcollet assembly 2516 to lock a dissection tool such as shown in FIG. 20Ato rotate with an internal shaft.

[0157]FIG. 26 depicts a cross-sectional view of the angled adaptor 2510fixedly interconnected with the attachment 2514. The angled adaptorincludes a housing 2524 having a proximal housing 2526 alignable withthe motor 12 and a distal housing 2528 extending at an offset angle fromthe proximal housing 2526. The motor coupling end 2512 of the proximalhousing 2526 includes an internal cavity 2538 adapted to matinglyreceive the distal portion 51 of the motor 12. As previously describedwith respect to FIGS. 2A through 3 and in a similar manner, the cavity2538 includes flats 2540 configured to engage one of the Double Dsections of the distal portion 51 upon rotation to thereby lock theangled adaptor 2510 to the motor 12. Extending within cavity 2538 is adrive shaft 2530 having a power coupling end 2532 that includes aninternal alignment bore 2534 and adjacent external drive portion 2536.Opposite power coupling end 2532, the drive shaft 2530 includes a powertransfer gear 2544 coupled through an offset angle to a power transfergear 2546 of a power shaft 2548. It will be understood that rotary forceapplied to the external drive portion 2536 may be transferred throughgears 2544 and 2546 to the power shaft 2548. Further, the tool couplingcollet assembly 2516 may be actuated by movement of section 2518 tolockingly hold a dissection tool such that the rotary force of the motor12 may be transferred through angled adaptor 2510 to the dissectiontool.

[0158] Reference will now be made to FIGS. 27 and 28 illustrating thepower coupling of the motor 12 and the angled adaptor 2510. FIG. 27shows the motor coupling end 2512 disposed over the distal portion 51 ofthe motor 12. The angled adaptor 2510 has been rotated with respect tothe motor 12 such that the collet assembly 2030 is in the lockedposition as shown in greater detail in FIG. 22B. The drive shaft 2530has been advanced to position the drive portion 2536 within the drivesocket 2043 such that the alignment pin 2072 extends within thealignment bore 2534. The lock ring 2080 has been moved to urge thelocking ball 2060 into engagement with the drive shaft 2530. As shown inmore detail in FIG. 28, each of the locking balls 2060A, 2060B, and2060C engages a respective driving flat 2550A, 2550B, and 2550C tolockingly engage the drive portion 2536 for rotation with the rotorshaft 2040. In the preferred embodiment illustrated, cylindricalportions 2552 extend between each of the driving flats 2550. Thecylindrical portions 2552 define a maximum outer diameter of thesubstantially triangular driving portion 2536 that is smaller than theminimum inner diameter of the substantially hexagonal driving socket2043. Thus, in this preferred embodiment, the drive shaft 2530 may beadvanced longitudinally into the driving socket 2043 without regard tothe rotational orientation of the driving flats 2550. The locking balls2060 may rotate the drive shaft 2530 to the proper orientation as theballs are moved from the unlocked position to the locked position. Itwill be understood that in this implementation, collet assembly 2030utilizes locking balls 2060, not drive socket 2043, to transfer rotaryforce while the adaptor 2510 is held firmly to the motor 12 to inhibitlongitudinal movement.

[0159] The angled adaptor 2510 described above may be interconnectedwith the motor 12 in the following manner. The motor coupling end 2512of the angled adaptor 2510 is axially aligned with the motor 12 andpositioned over the distal portion 51. Movement of the angled adaptorover the distal portion 51 also brings the drive shaft 2530 into thedriving socket 2043 such that the alignment pin 2072 is positioned inalignment bore 2534. With the angled adaptor 2510 fully seatedlongitudinal on the distal portion 51, the adaptor is rotated withrespect to the motor to thereby lock the adaptor to the motor and tolock the drive shaft 2530 to the rotor shaft 2040. A dissection toolsuch as that shown in FIG. 20A may then be inserted through theattachment tube 2514 and into tool coupling collet assembly 2516. Thesection 2518 may be rotated to lock the dissection tool for rotationwith the power shaft 2548. The section 2518 may be rotated in theopposite direction to unlock the tool coupling collet assembly 2516 tochange dissection tools.

[0160] While an angled adaptor has been shown and described, it iscontemplated that the present invention may also be utilized with astraight adaptor. Further, while rotary dissection tools have been shownand described, it is contemplated that adaptors having power couplingarrangements in accordance with the present invention may be used withor coupled to oscillating and reciprocating cutting implements. Stillfurther, the angled adaptor 2510 may be configured to permit removablecoupling with the attachment tube 2514 by utilizing tool couplingassemblies as previously described herein, for example, but withoutlimitation, coupling assembly 2030.

[0161] The above description of the invention is merely exemplary innature and, thus, variations that do not depart from the gist of theinvention are intended to be within the scope of the invention. Suchvariations are not to be regarded as a departure from the spirit andscope of the invention.

What is claimed is:
 1. A surgical tool for use in the dissection ofbone, biomaterials, and/or other tissue, the surgical tool comprising: arotary shaft including a cavity having a longitudinal axis; a driveshaft assembly having a first end coupled to a dissection element and asecond end having a centrally located aperture extending along at leasta portion of the drive shaft, the second end configured for insertioninto the cavity; and a male member carried by said rotary drive shaftand extending along the longitudinal axis, the male member configured toextend into the aperture of the drive shaft assembly.
 2. The surgicaltool of claim 1, wherein the drive shaft assembly is housed in anadaptor housing and the adaptor housing including a dissection toolcoupling assembly.
 3. The surgical tool of claim 2, wherein the adaptorhousing includes a first portion in substantial alignment with therotary shaft and a second portion extending at an offset angle from thefirst portion.
 4. The surgical tool of claim 2, wherein the dissectionelement is releasably coupled to the drive shaft.
 5. The surgical toolof claim 2, wherein the rotary shaft is coupled to a motor having amotor housing and the adaptor housing is selectively coupled to themotor housing.
 6. The surgical tool of claim 5, wherein the adaptorhousing includes a locking member releasably engageable with the motorhousing to resist longitudinal movement.
 7. The surgical tool of claim6, wherein locking member is actuated by rotation of the adaptor housingwith respect to the motor housing.
 8. The surgical tool of claim 7,wherein the rotary shaft further includes a tool coupling assembly forreleaseably interconnecting the rotary shaft and the drive shaftassembly.
 9. The surgical tool of claim 8, wherein the tool couplingassembly is actuated by rotation of the adaptor housing with respect tothe motor housing.
 10. An adaptor for use with a surgical dissectioninstrument having a rotary drive shaft assembly with an axis of rotationand an alignment member, the adaptor comprising: a drive train assemblyhaving a first end with a first axis and an opposite second end; analignment channel defined in said first end and extending along thefirst axis, said alignment channel configured to engage the alignmentmember of the rotary drive shaft assembly to align said longitudinalaxis and the axis of rotation; and a drive surface defined adjacent saidfirst end and configured to couple with the rotary drive shaft assembly.11. The adaptor of claim 10, further including a tool coupling assemblyadjacent the opposite second end for coupling with a dissection tool.12. The apparatus of claim 10, wherein the drive surface issubstantially triangular.
 13. The apparatus of claim 10, wherein thefirst end and the second end are disposed at an offset angle withrespect to each other.
 14. The apparatus of claim 11, further includinga dissection tool configured for coupling with the tool couplingassembly.
 15. The apparatus of claim 10, wherein the surgical dissectioninstrument includes a housing and the adaptor further includes anadaptor housing surrounding the drive trains assembly, the adaptorhousing including a locking member for releasably engaging the housingto inhibit longitudinal movement.
 16. The apparatus of claim 15, whereinthe locking member is urged to releasably engage the housing by rotationof the adaptor housing with respect to the surgical dissectioninstrument housing.